German Patent Document 36 10 022 describes an apparatus which can be utilized to produce corrugated sheet having closed corrugations so that the lateral edge surfaces are plane-parallel and thus can be abutted along seams. The formation of such plane-parallel edge surfaces enables communication of the plates together along seams which are transverse in the direction in which the corrugations run. The seams can be welded or otherwise connected in abutting relationship, since the abutting edges of the sheet metal plates do not have any open spaces or hollows where corrugations might meet. The device does, however, have the disadvantage that the fabrication of closed corrugations, i.e. corrugations which do not run from one edge of the sheet to an opposite edge of the sheet is difficult technologically and expensive and the fabrication of tools which are capable of stamping closed-end corrugations from the sheet during the corrugation forming operation is extremely costly. In addition, the earlier technique has a tendency to reduce the thickness of the sheet metal in the regions of the closed end of the corrugations because of the excessive stretching of these ends necessitated by the deformation of the sheet to provide the closed end.
Other apparatus is known by means of which open end corrugations can be formed over the entire length or width of the sheet. The advantage of such an apparatus is that the corrugations can be formed with stamping tools which are relatively simple and, further, the sheet thickness tends to be constant in all regions of the corrugation. However, connection of corrugated sheet metal plates with the corrugations running to the connected edge is complicated and difficult. For example, the weld must meander along the contours of the meeting corrugations or open corrugations must be filled in. The closing of openings formed at the corrugations is expensive and time consuming.